A radio communication system of the next generation to implement higher-speed communications than the currently-operated 3rd generation and 3.5th generation radio communication systems includes LTE (Long Term Evolution) standardized by the 3GPP (3rd Generation Partnership Project), which is the standardization organization for the radio communication systems. The LTE-advanced in which the LTE is advanced is planned to employ relay transmission using a radio relay station referred to as a relay node (see, for example, non-patent literature 1).
The radio relay station is a relay base station with a small output, which can be connected to a radio base station (a macro base station) via a radio link. A radio terminal connected to the radio relay station communicates with the radio base station via the radio relay station. The installation of a radio relay station in a cell edge, coverage hole or the like of the radio base station makes it possible for a radio terminal to perform communications under better conditions by indirectly communicating with the radio base station via the radio relay station, than by directly communicating with the radio base station.